First of all you have to collect enough material  from tasks or from drops from invaders.

The material you need is depicted in circles, you will also need some silver, when you can build something you will see everything is ticked. but beware there are many things to consider when forging equipment, an important one is, if you are wanting to make immediate use of it , make sure that your hero has advanced enough.

I am pretty sure there are some official links to videos,and there must be one on this topic.The links are in Video Tutorials on the forum.Also various ideas on game play throughout the forum.

If you cant understand me , or the videos , ask again.

On the first page the required items are in squares, on the next page where you hit craft they are in circles

Have you found the cunningly hidden arrows to change pages?