When you create your email signature in HubSpot there are two boxes. The top one is the backend coding that HubSpot uses to display your email signature. The images you use in your email signature will have to be stored images on the internet somewhere, and HubSpot is just going to pull that image from a link reference in your code section.
What I would do if I were you is create an email signature in something like Gmail, save it, and then copy and paste it into your HubSpot account. See if that works. If not, add this code into the top box of your edit signature page (the one with the code):
<td style=“font-family: arial, sans-serif; margin: 0px; padding: 0px 8px 0px 0px; width: 1px;” valign=“top”><img style=“border: 0px; vertical-align: bottom;” src="
INSERT YOUR IMAGE URL ADDRESS HERE
" alt=“” /></td>
So, for example
<td style=“font-family: arial, sans-serif; margin: 0px; padding: 0px 8px 0px 0px; width: 1px;” valign=“top”><img style=“border: 0px; vertical-align: middle;” src=“https://ci6.googleusercontent.com/proxy/U_oOJJVYiboz-gFpOC4_OSTYCTYnp--7QslqcBatQ62d3h3bb8HYDmYvL1bfq761aJ08ZoMUiLQH4062sljqfM8Yzje7qrEuSL40FgcRxGq2Xw=s0-d-e1-ft#https://img.newoldstamp.com/p/000/002/u779.png?56900c2b6c324” alt=“” /></td>
Will show the photo that can be found at: https://storage.googleapis.com/gweb-uniblog-publish-prod/static/blog/images/google-200x200.7714256da16f.png
If you need a place to upload your logo to, first do so here http://tinypic.com/ and then get the url for your image after you upload it and use that url to insert in the code above.
Maybe that helps? Maybe not.
-JustinH