Most modpacks on the Feed the Beast launcher also come with a server version for you to easily setup a server to play with your friends, you can download the server version to setup yourself easily by going onto the launcher and selecting the modpack you want to play, you can then click the "download server" button, this will open a tab in your web browser and download the server zip for that server. Our hosting page has a guide on how to install the server software. Alternativly you can buy a server from a FTB server hosting company, they will setup the server for you so all you have to do is play!