if i create my own plugin, how do i call the plugin in a template?
 

I'm assuming you can't input php code directly into templates so I was wondering how I can call a plugin that I have created?

Plugins are called by hooks. If you look at the dropdown for hook locations in the plugin page, you'll see a ton of them. They are all located in the php code. So, if you pick "postbit_display_complete", you can do a search in your files and find that one of the places it is located in the file class_postbit.php around line 314:
So, you would be inserting code right there. You can see that several lines below that is where the postbit (or postbit_legacy) and the postbit_wrapper is rendered. So, if you want to insert something into those templates, that is a good hook location to pick.

You dont call plugins in templates, you render templates in plugins.

Alright, so say I create a plugin with the forumhome_complete hook, what would I insert into the forumhome template to execute that specific plugin? If I insert the code you have posted above, won't that execute every plugin associated with the hook?

What I'm wanting to do is take the (modified) code from the php file I have running for the news script at http://pokemontopaz.net/ and put that into a plugin then have it display that on the forum home template - to create a news box.

So basically, the code is pretty much already written and just needs to be inserted into a plugin. I'm just not sure how to call the plugin in the template without executing every plugin associated with the hook.

The code I posted above was showing you what the hooks look like in the existing code. That isn't code you would put in a plugin.

You don't call plugins in templates. Plugins can be used to render templates. Go download some modifications that do something similar to what you want and see what they did.