Words but this guide should get you there.
Right click on your Epson TM-88IV printer and go to <Printer properties>.
Go to <Utility> and click on EPSON Flash Logo.
Under <Bitmap Selection> tab, click on <Open file...> to select your black and white bitmap (BMP) logo file.
Go to <Logo Upload> tab and click on <Upload> - <Device> to upload the image to the printer memory.
Do a test print under <Logo Printout> tab by clicking on the <Print> button, you should see your logo being printed. May need some trial and error to align the logo to your desired position.
Under EPOS, go to <Hareware setup>, under <Print Header Logo>, enters the following code.
If you are using TMU-220D, please use these code instead,
Save your settings and the logo should printer for every receipt.