Why not look at your problem from a different point of view, and work on your general model making skills & experience, even if it's not a motorbike?
Get a cheap 1/72 WW2 fighter, like a Spitfire or Zero; they're fairly simple, that's how most of us started. Just use it as an exercise in learning & trying techniques.
That includes glueing, filling, sanding, painting,
decals, etc, etc. - and patience! No need to buy the camouflage paints, just use those you have for bikes - black, red, silver? it will look a bit silly, but you will learn
Go to your library and see if they have a suitable book. Even if it is for ships or planes the techniques will be more or less the same. Or buy a suitable book - Surf the Net
Browse round your newsagents, there are several magazines available. I don't know if there is one specifically on motorbikes, but one on general modelling, ie all subjects, will show you techniques & ideas - dry fitting, trimming, filling, sanding, are pretty much the same whatever you make. Now & again magazines have a series of beginner's articles
If you buy it regularly, you will start to see how the techniques are used, get used to the jargon, and see how other people have done things
Click on the green banner at the head of this page, for the
Scale Model Shop -
Scale Model Shop. that will show you many of the tools, paints, and accessories available. There are other model shops; Surf, or look at the adverts in model mags.
I've just been on YouTube and put 'basic plastic model making' into the search box, and got about 7 or 8 pages of videos
Again, I've put 'plastic model motorbikes' into YouTube's search box and got 6 or 7 pages of videos