i have included a css file to my bootstrap file but it dosent seem to work
You need to specify the directory
Create a new CSS file. In the head area, refer to your CSS file. In this case the file was named style.css - but the name is of course individual:
<link href = "style.css?v=1.0" rel = "stylesheet" type="text/css" />
You should save the style.css file in the main directory of the webserver.
I also see that the } is missing in your code but that's I think only an issue of your post.
Normally bootstrap.css is the standard CSS file for bootstrap. I strongly recommend you not to change the file because things will get too complicated by this. It's better if you overwrite the CSS within your newly created CSS file. Its also possible that you have some caching issue.
Did you clear the browser cache and other caching methods?