Don't listen to anything sheepish has to say imo, he is a shit map maker and even worse at explaining things.
If you want to take all the hard work out of mini map making you can always use the minimap maker that Nota made, it can be found in the download section of newerth. However if you want a nice looking mini, then really the best way to make it is by following the guidelines set out in Zealotts tut
http://www.aus-newerth.com/forums/index.php/topic,284.0.htmlYou can easily follow this process using GIMP or Photoshop, and I am pretty sure you can get gimp for free? Making a good mini map is a real art, and I would strongly recommend opening up some of the classics like eden to really get a feel for what a good mini looks like.
Any other help you need, feel free to ask.