I2P is pretty straight forward. You can either install the .deb, the java package from I2P's site or use I2P+ which is what I prefer ( https://i2pplus.com/ ). If using the .deb, just make sure you update it afterwards since the package is almost certainly outdated.

If using a VPS, you'll have to tunnel your localhost desktop traffic to it. I do something like:

ssh -fTNL 4444:127.0.0.1:4444 -L 7657:127.0.0.1:7657 -L 7667:127.0.0.1:7667 -L 7658:127.0.0.1:7658 -L 6668:127.0.0.1:6668 user@remote-ip -p XXXX

Port 4444 = local proxy settings (for browsing I2P network sites), 7657 and 7667 for the console UI in your browser (7667 is SSL, 7657 non-ssl), 7658 is the built in webserver and 6668 is IRC. "XXXX" would just be whatever your remote SSH port is if not 22.

Out of the box, stock I2P is... lacking. The system uses "subscription lists" and an "addressbook" to access network sites. ramble.i2p won't work out of the box, simply because it's not published on their stock subscription list, which is about 40 random network sites of which half of them work, half the time. You either have to add sites to your addressbook manually or by using their "address helper links" or using a published subscription list which contains a lot of sites that'll be added to your addressbook. Check out /f/i2p for more on that.