You can add a banner to your signature which appears in your Community forum posts. By default your signature is blank. There are actually two signatures you can change, one for the desktop view and one for the mobile view. Both of these signatures can contain plain text or HTML code and it is this HTML code that allows graphics, eg banners, to be incorporated into your signatures.
The desktop signature area is 550 x 95 pixels and the mobile signature area is smaller at 310 x 80 pixels. The whole signature should not exceed the respective dimensions otherwise they will be trimmed to fit eg if your desktop banner is 550x120 then the bottom part of it will be cut off.
For your banners you can either use any of the giffgaff default banners or you can use your own. To use your own banner you need to host it on an external image hosting site, eg postimg.org or tinypic.com. Whether using the giffgaff banners or your own it is the URL to your chosen image that is used in the steps below. Use your creative talent, but avoid using content that might be copyrighted or belong to someone else.
In either Mobile and Desktop views you will see a text box labelled Signature or Mobile Signature where you need to enter the text or HTML code for your banner. An example of the code using one of giffgaff's default banners is:
Where you need to replace "[YOUR GIFFGAFF USERNAME]" with your giffgaff username (in order that you correctly receive payback for your affiliate link). If you have hosted your own banner's graphics on an external site, place the URL to your banner in the "src" field, eg: