As Graham said, a search will give you probably 100's of posts to check out. Please use the search feature of this site. Graham also mentioned the links section in this forum. I'm not sure what other type of guidance you are seeking.
There is no template that will just let you fill in the blanks and generate a test plan. Test plans require thought. If you are looking for a "paint by the numbers" template, you will not find one.
Read the posts that you find in your search and you will get a feeling for what goes into a test plan.
Many of the posts you pull up when you do a search say to "do a search". It would have been quicker to advise that the "downloads" tab contains a Test Plan template.
The first time I have a staff member write a test plan, I GIVE THEM THE TEMPLATE. They don't have to spend all day looking for one.
There are, in fact, templates that you can fill out, pretty much "by number", that will give you a decent result. That doesn't mean it doesn't require any thought. Even paint by number requires you select and use the correct color for the correct section...
And I know what you're thinking, Wasabi Master, but I just don't agree with you. This time. There are other times, however, when I think you're reading my mind...