Firstly save the image of the signature somewhere on your PC (if this is in an email right click and choose save as picture)
Then in Oyez, Go to the Tools tab on the top taskbar then into Signatures
Then you need to click the little folder next to the red cross to add in a signature and give it a name.
Then click browse and go to the folder on your PC where you saved the signature image, once selected you can click save
Now click into the field on the form where you need to enter the signature and simply right click then select Insert signature and you will get the option to choose which one to insert from those you saved as above
Then go to File>Export as PDF to save a PDF version of the form with the signature embedded: