Get fixtures into the scene
Open the Library panel on the right.
Search by name, filter by Conventionals / Moving Heads, add a manufacturer filter, or press Show my fixtures to see only what you have imported. Each card is one mode of a fixture — Mode 1 · Wash, Mode 4 · Pixel RGBW — because the mode decides the channel count you are patching.
Drag a card into the viewport to place a fixture.
If a fixture you need is not there, you have three ways in, all under File › Import: GDTF, OFL, and MVR (which brings a whole scene).
File › Import › Patch (CSV) is a different thing and worth being precise about: it takes MagicQ CSV only, and it imports the patch alone — addresses and universes, not the fixtures themselves. The fixtures have to exist in the scene already, from the library or from a GDTF/OFL/MVR import.
For anything you do not have a file for, connect to GDTF Share and search the full catalogue from inside FlexViz:
Sign in with your gdtf-share.com account. The toolbar then shows the connection: