Currently multiplayer support is a little bit broken. However, I've fixed it in the upcoming update and it should be fine by the time I release it. As for modpacks, they're highly encouraged to be made. You just have to credit me and The_Slayer2, along with linking back to either the Curse page, the PMC page, or the MCForum page. If you post a modpack with the mod in it, please send me a link to it. I'd love to check it out.

(Use JEI for the crafting recipes)

The next update will have an in-game guide that will give you info on everything, however there currently is a W.I.P wiki with not a lot of content on it yet.
To get to the Frozen Lands, you have to craft some Frozen Portal Frames and build them like a Nether portal, and light it with a Flame Coin.

To get to the Boiling Point, you have to search the Nether for a couple structures. One being an unbreakable structure with a lock and chain on it, and the other being a small dungeon with Hellbots spawning. Kill enough Hellbots, and you can get materials for the Boil Key. One you have a Boil Key, you can unlock the gate on the other structure which contains a chest with the portal frames within them. The portal is lit with a flame coin.

To get to Euca, you have to do kill the Nether bosses and use the Euca Portal Pieces that they drop to craft some Euca Portal Frames. Here are the recipes for the boss spawners, which are crafted in a Summoning Table. The Soul Watcher is the only boss that requires you to go to the Boiling Point first. Within the Boiling Point, you have to find a structure that has multiple cages. Spawning from these cages are mobs that drop the Sizzling Eye, necessary to craft the Soul Watcher spawner. Once you've killed all three bosses, you should have all the Portal Pieces necessary for the Euca Portal Frame.

For the Depths, it's much easier. All you have to do is kill some Euca mobs and find a structure within Euca that spawns Goldbots and Silverbots. These guys will drop some materials necessary for the two boss spawners. Both bosses will drop some Depths Portal Gems that can be used to craft the Depths Portal.

Corba is a little bit more interesting. You have to kill some Depths mobs, and locate another structure in the depths that has a lock on it. Another structure is the one resembling a platform, which holds the Guardian NPC that can trade you some weapons, along with the key that is necessary to open the gate. Once you open the gate, you'll find some unfriendly mobs that are necessary to rarely drop the Dark Orb, which is necessary for one of the boss spawners. Inside the chest is also some loot, along with some Scales necessary for one of the bosses. Once you kill both bosses, you can craft the Corba portal frame, which is placed like an End portal. Use the Demonic Eyes that you got from killing the Soul Watcher to fill in the portal frame slots. It's a little bit tricky, and you have to place them in an even way so that they are all facing the center. If you did it right, the center should fill with the Corba Portal.

Terrania is much simpler again. You have to go around Corba, looking for a gigantic tree structure that has some Overseers spawning from the top. These guys will drop some valuable loot necessary for the Corba bosses. They will also drop some rocks and eyes that are used to to trade with the Tordos, which are also found in a rare village structure. One of the Tordos will trade a key that is necessary to unlock the Elder spawners at the top of the tree. Once you unlock the spawners, you can kill the Elders for some Overseeing Tablets. These, along with the Overseeing Eyes, will be used to create the Sentry King boss spawner, which will drop some Terrania Portal Gems.

Cloudia is simple too. Once you're in Terrania, you must look for a rare tree structure that stands out from all of the rest. On top will be some Purplians, which will drop some Purple Powder and some other necessary loot for the Terranian Protector boss spawner. The other materials necessary are rarely dropped from Terrania mobs (just like the other dimensions). Once you kill the Terranian Protector boss, it will drop some Cloudia Portal gems that can be crafted into the Cloudia Portal Frame, and can be lit by the flame coin to create the portal.

And that's pretty much all of the dimensions for now. The next update will have 4 more dimensions, along with some Nether content and an in-game guidebook. I'll also be working on the Wiki a lot more, so that the information will be much more accessible and accurate.