how many times do we have to feed a rabbit in a day?

I hope they're not 1 month old. A 1 month old rabbit should still be nursing from their mother. They're not fully weaned until they're 2 months old.

Young rabbits need constant access to pellets, hay and water - NO TREATS AND NO VEG!

Read this:

http://rabbit.org/faq-diet/

They should still be fed by their mother at this age, baby bunnies aren't weaned until about 6-8 weeks. However if this is in no way possible, then a high protein milk supplement with pellets should be ok. Also small amounts of mixed feed, not too much of everything so they don't overindulge on one particular thing. Vegetables should be introduced to bunnies around 12 weeks of age, in small quantities and one at a time.

There is no specific time as such.. you are supposed to keep the food (specifically carrot and spinach) inside the cage and the rabbit can have it when its hungry.. but if it's a new born you have to feed it after every two hours... do not feed a new born, carrot or anything hard. Its suppose to be fed by the mother rabbit...

=)