Obtain a free paintshop type of software if your computer doesn't already have one installed.
Open the paint software and select the "Text" option. Chose a font style, color and size that is appropriate for your school and its colors.
Place the text in the center of the screen on which you're working. Make a cheerful slogan to express your school spirit.
Put another text block beneath the slogan. Have it say the name of your school.
Place a sheet of iron-on transfer paper, face down, into the printer.
Print the colorful text on the transfer paper.
Select some clip-art of your school's mascot and paste the clip-art into a new template on the paint program of your choice.
Center the image on the template.
Print the picture out on another sheet of iron-on transfer paper.
Use the scissors and cut around each printed template. Cut carefully so as not to cut into the actual clip-art and fonts of the designs.
Plug in the iron and turn it on its hottest setting. Allow it to sit for approximately 10 minutes to achieve the right temperature.
Place the decal featuring your spirit slogan across the chest part of the front of the blank T-shirt. Make sure the decal side is facing against the material of the shirt.
Place the hot iron on top of the transfer paper and adhere the design to the shirt by pressing the iron and making sweeping motions outward from the center of the paper. Do this firmly for approximately 60 seconds.
Place the transfer paper featuring the mascot or other design, face-down beneath the slogan and repeat step 13.
Carefully peel back the transfer paper from the decals on your shirt. Allow the shirt to set for an hour before wearing it.