Welcome to the Elite Galaxy commander!
Yeah that's a bit confusing. As
@Jmanis said you have to use the mission depot. The link below gives some information on the mission depot. The picture in the article shows the depot at the delivery location. To get your cargo you use the depot menu at the pickup location. You access the depot menu via the mission board by selecting the mission(s) you've accepted shown at the top of the page under "Ongoing Missions".
The Mission Depot is a menu where pilots can collect and deliver cargo for trading missions incrementally and view their progress. It is available for both Team Missions and solo missions.[1][2] For trading missions, pilots can buy the necessary commodities directly through the Mission Depot if...
elite-dangerous.fandom.com
Maybe you've already found most of the resources listed below. If not, have a look at them and in any case don't hesitate to ask questions here in the forum.
In-game help is available in the form of menu links to the Pilot's Handbook and the Codex (right-hand cockpit panel 1st tab).
For a very good beginner's guide see:
An in-depth beginner’s guide to Elite: Dangerous.
Tutorials covering all aspects of the game, many of them in the form of YouTube videos, are available from
ED Tutorials.
There is a wealth of useful information available in these forums spread out over hundreds of threads. Thanks to commander
@Alec Turner you can access all of that information and more via a single thread:
Alec's best of the forum (and elsewhere) [v2].
Here is a good guide on
the background simulation (BGS) that simulates the economical and political changes caused by player actions in inhabited systems.
Also check out the
inara.cz and
eddb.io websites with (almost) realtime info on practically everything in the game.
The
coriolis.io and
edsy.org websites let you design your ships before buying them.
There are many more
Tools and Websites created by fans that make life in the galaxy better.
And last but not least, the
Elite Dangerous Wiki contains extensive information on nearly all aspects of the game.
o7