if this is a windows computer basically you right click on a blank section of the desktop and choose display properties or personalize.
then you want to find the display settings and make the
RESOLUTION which is a set of 2 numbers higher.
there will be a selection of them to choose from. choose higher ones.
getting there is a little bit different in each version of windows so i need to know what version you are using before i can get more exact instructions.
or i can log in remotely to do it for you if you want to pay a little bit extra.