i want to add the IDEA logo to my website. How can I do that???

I assume you made your own web site.

Go to your IDEA account and click on 'Promote My Page'. You have a choice of several images. Those you can copy and import into your own website. There you make sure that the image has the IDEA information as a hyperlink, and you are done.

I put that on my home page at www.meltnc.com if you want to check :-)