Help please how do you make ocmod to add meta desciption to a certain module

hi everyone just hoping someone can tell me how to make an ocmod to add a meta description to this page http://oc-marketplaceaddons.webkul.com/ ... lercentral
or am i best using events

i bought the module from them and it doesn't have a meta description or anywhere to put it so having to work out how to make a ocmod
I'm trying to work out how to add

<meta name="description" content="testing testing">
<h1>Marketplace sign up page </h1>
i never made ocmod before
how do i work out <file path=

1. Write to developer to fix...the issue
2. You can download an ocmod extension to see how is made.

Well, you find most everything important on such here:
viewtopic.php?f=202&t=207547&p=736850#p736850
Ernie