Hi rutuma,
Here is the steps for installing webservice in SharePoint folder.
1. Open the IIS of machine in which you want to install web service.
2. Expand websites then you will find SharePoint - 80.
3. Right click on SharePoint - 80
4. Go to ‘New-> Virtual directory’. Then Virtual Directory creation wizard window will be opened.
5. Click ‘Next’ on that window and enter the name you want in ‘Alias’.
6. Click ‘Next’ and in the Path give the path where you have placed web service files.
7. Click ‘Next’ and Check the check boxes.
8. Click ‘Next’ and finish the installation.