An RFP template can be used to create RFPs in short-order. An RFP template is a collection of sections. So you will want to create these re-usable sections first.
Both RFP templates and sections are created and then available in the Library.
But, if you write an RFP and want to save it as a template, you can do that as well. In the details page of your RFP, check out the right-hand side where you can save the entire RFP as a template in the Library.
If you would like to use a template you have already created when drafting a new RFP Section, simply click on Add Section in the lower left hand corner of your RFP, then this page will come up. Select the Create from Library tab at the top and Add Sections at the lower left hand corner of the page.