You may not have one. If you don't then just create one using notepad and call it .htaccess and upload it to the main directory of your site. If you do have one you can just download it via ftp and edit it in notepad. Make sure your ftp client is set up to view all files otherwise you may not see it.
Ok, I have 3 sites on my server though so will it be in the root of all 3 sites or will ther ebe one in each individual directory for each site?
If there isn't one in the individual sites' root directory, the one in your server root will be used. So it depends if any .htaccess exists on each of your site. If there is one in your server root AND in your individual site root, then the latter will be used.
Ok thanks I found it and its in the main root directory before the sub folder sites. Thanks just needed to know what program to open the thing with
Open it with notepad but make sure you don't change the name. If you have a cpanel host you can use the file manager and directly edit the file
btw, .htaccess often is hidden and, for example, in my ftp client it's not shown. I need to manuall type ftp commands: GET .htaccess to get it or DELE .htaccess to delete it.
you can usually set up the ftp client filters to see these hidden files. That way you don't have to use commands or anything :d I did it with cuteftp.