You can do it in the specification tree
if you wish.
In the Pad Definition dialog box that appears,
enter 90 mm as the new length value.
The part is modified accordingly.
Now select Part Body.
Select Edit > Properties and click the
Graphic tab to change the color of your part.
Set the color of your choice in the Color
combo box and click OK.
To have details about how to change graphic properties, see
Infrastructure User's Guide Version 5.
The part now looks like this: