There are thousands of people who wear coloured lenses, it's not much different to people wanting to dye their hair a different colour so don't be embarrassed about it.
However you must remember that the short and long term health of your eyes is paramount. And the same rules apply whether you wear contact lenses to correct your vision or whether it's for cosmetic purposes.
Try not to wear your lenses all day every day because lenses on the eye reduce the oxygen getting to the eye which is very important in the normal function of the eye.
Try to wear them upto ten hours but don't always aim for ten..this is just a general safe upper limit. and don't forget these are general guidelines and because every individual eye is unique, the same rules may not cecessarily apply to you.
Make sure you always clean the lenses throughly after wearing them, never sleep in them.
Most importantly choose a good optician who will advise you well about all aspects of lens wear.