Open Cricut Design Space and Click "New Project" in the top right corner.
Click "Upload Image" and click "Browse".
Click "Open", "Continue" & "Apply & Continue".Select "Flat Graphic" and click "Continue". Give your image a name, place it in a folder (optional) & finally click "Upload".
Click on the image, then click "Offset". In this case choosing 0.55 worked well. Click "Apply".
If your image has unnecessary holes in it, change the "Offset" operation temporarily to "Basic Cut".
Click "Contour" and then click "Hide All Contours".
Change the operation on the offset back to print then cut. "Then change the color of the offset to the color you prefer.
Select the image and the offset and choose "Flatten".
To add this to a adult T-shirt I recommend using the largest size possible to print on paper. To do that, click on the exclamation mark in the layers panel and choose "Auto-Resize Image".For child sizes, measure the T-shirt, and decide the size depending on that.