Hi Bart2812, and welcome to the forum! It would help a bit if you told us what version of the game you're using (1.74 would be recommended) and what OS you're running (I'm assuming Windows). There's lots of information on OXPs (Oolite eXpansion Packs) on the wiki
: here's what it says about installing them on Windows:
If the installable package was used (post Jan 06) then the AddOns folder needs to be created in C:\Programs Files\Oolite. Note that this applies if the default installation location is used. If the install location is changed then use the path to the Oolite folder that corresponds to your installation. If the GNUStep dedicated versions (pre-Jan 2006) is used, then the AddOns folder must be created in the oolite.app folder.
After unzipping the file, make sure that it is the OXP folder that put into the AddOns directory – some zipped OXPs can contain a top level folder with a readMe file, and the actual OXP folder is a level further down. If this is the case, move the item with the [/b].oxp[/b] extension into the AddOns folder.
Some OXPs can add more to your game than you might want, especially if you're just starting. My advice is to add them a couple at a time and see which ones suit your style of gameplay (and your idea of the Oolite universe).
If you want to give yourself a docking computer, you can edit your savefile – which you should make a backup copy of first – using a text editor (please note, though: one Windows text editor – unhelpfully I can't remember which one – should NOT be used as it plants all sorts of hidden characters all over the shop and generally will ruin your day. I'm sure a PC user will be along shortly to tell you which one!).
I really would recommend learning to dock manually, though, as a docking computer can get damaged in combat and you'll need to dock manually anyway. The good news is, it's a lot easier now: there's a buoy conveniently placed outside every main station: fly to that, stop, point up towards the station and you'll be bang on line. Plus, you can see inside the dock now: it's not just a rotating rectangle any more, so it's easy to see if you're on target!