On the dashboard, select New Proposal near the top. The New Proposal link is found on any of the four tabs (My Tasks, My Proposals, Watch List, All Proposals). 

Once you have selected New Proposal, you will see a list of all available proposal templates. If you do not see the proposal form you are looking for, select Next 10 at the bottom of the page.

Once you identify the form you would like to use, select the check icon to Start Proposal. You will be taken to the proposal template to begin filling out.