Hi, and welcome. Your first stop should be to check out the "stickies" in the Technical Write-ups section. There you will find some helpful stuff like this: https://tw200forum.com/forum/technica...back-life.html , https://tw200forum.com/forum/technica...tch-works.html, as well as find download-able copies of the service manual.
A little more info on the history of the bike would be useful for our members, such as has it been sitting unused for a while? How long? What is the mileage?
Bikes that have been sitting can get their clutch plates stuck together. I would read through that first link and make sure you first don't do more harm by the way you try to get 'er running. An oil change and proper clutch cable and drive chain slack adjustments may get the clutch back in order, along with some rocking back and forth while trying the gearshift. If not, the service manual and some searches will help get you all fixed up.
FYI- the integrated search feature can be, well not the most helpful sometimes. You can use Bing or Google and limit your searches to this site by typing this in the search bar...
site:tw200forum.com clutch problem (or whatever search term you are hunting for)
This route often yields better results for me. Good luck!