If you are new to Rapidweaver can I suggest you take a look at these free video tutorials.
Adding an image using html will work in Rapidweaver, but that isn’t the easiest, or generally the best way.
The most basic way to do this is using a Styled Text page, simply drag the image you want to use as a thumbnail onto the page. You then go to the > Format, >HTML, menu you can align the image Left or Right of any text you have. To add a link to another page select the thumbnail image, right click and choose the “add link” option from the menu, select ‘page’ from the first drop down and select the page you want to link to (which you should have already created).
Hope this helps getting you started, but I strongly suggest you take a look at the free tutorials available, because Rapidweaver is different to Dreamviever and you won’t get the most out of it if you try to use it in the same way.