To use any of the games online features, like the bonus paintmod that any customer gets for free for just registering their game and the Venture Feature released as beta in v1.50, you need to set up an account on www.egosoft.com for the online community (same as your forum account!).
Once you are logged in and registered, the Online Features menu should look like this:
The additional options at the bottom of the Online Features Menu (not visible in the above images) relate to the Online Ventures Feature. Those additonal options are explained on the Venture Feature page.
Paint mods available in every restarted game:
Right click on any of the ships you want to apply the paint mod to and select "REDESIGN" from the list of actions (or select the "REDESIGN" option at the computer panel in front of docked ships). There will be three tabs with the rarity categories of mods. The Foundation X paint mod is in the ENHANCED tab, and the rarer Obsidian X paint mod is in the EXCEPTIONAL tab.
If you do not see your mods listed in game in the REDESIGN action of one of your ships, after activating the game in the online community, try logging off and on again (or just restart the game, same effect).
If you have purchased the "Foundations Collector's Edition Content" upgrade, it will need to install before the Obsidian X paint mod appears in-game.