AutoCAD vector(DWG) to Adobe illustrator to add some colour

Hey there 👋 

I'm new to Adobe illustrator

Using a Mac Pro

I've drawn a (polyline) vector image on AutoCAD and have opened it up in illustrator, so far so good

Ideally I'd love to convert the lines to cooler brush strokes, but not 100% necessary

Mainly I'd like to colour the images sections different colours and am having trouble doing so..doesn't seem possible to drop a fill into the various sections and am wondering if I need to first convert the line format..?

Any advice welcome

Novice to tool bars and shortcuts on illustrator, please speak novice 😅 many thanks