just wanted to know if its possible (and how to do it) to insert weblinks and contacts form in some articles (or category description) using Jumi...
a) weblinks
Weblinks from a Joomla! component or just some links? I will suppose the first case.
In that case you have to write a php script that withdraw the required info from Joomla database.
Although you can do it using php functions and commands only I greatly recommend you to read some Joomla! documentation first - Joomla! has its own libraries and API which make developer's life easier.
Then the script has to be included into an article. For that purpose there is a Jumi plugin.
There are three approaches how to include the script into an article via this plugin. The most easiest way is saving the script as a php file. Upload it onto your server and in article just write
{jumi [pathnameof the script.php]} .... for Jumi v. < 2.1, or
{jumi pathnameofthescript.php}{/jumi}
b) a form
The general approach - developing the script + its inclusion - is the same as above.
I fell an obligation to express some warning.
a) Forms are very easy to design. And very easy to include. Very difficult (at the least for me) to protect them from internet bots: mindless machines they are living in the internet, searching for forms, filling them and pressing submit buttons. Before the form try to realize how you will protect the form. There are numerous ways: some of them are easy, some difficult, some working and the others for nothing.
b) the forms should be submitted somewhere. To database or by e-mail.
All of that rather complicate the fact the forms are very easy to develop themselves.
So be prepared on it before you begin.