How to take care of a strawberry plant that is in a pot?

It depends where you are at also where I'm at strawberries won't do well at this time of the year. 

depends, u can put in a large pot or in the garden, they do multiply. They are just like any plant, needs water and fertiliser and a lot of sun during the day.

How big a pot is it in? If you want any half-decent amount of fruit out of it then it needs to be in a pot with at least a 1 litre capacity. 

Otherwise, just put it somewhere sunny (outdoors or in a greenhouse; don't try to keep it on a windowsill), keep it watered (once the fruit starts swelling it will need watering daily if it doesn't rain) - any water will do, and once it starts flowering, feed it once a week with a high potassium liquid feed (liquid feed sold for tomatoes is perfect). 

It will perform better planted in the ground (assuming it's in a sunny spot), as it has more room to spread its roots and better access to water and nutrients, but strawberries still perform quite well in pots. 

It should also be noted that from mid summer it will start to produce baby plants on long stems (called runners). These can be rooted in pots themselves, and then severed from the parent plant once they have a decent root system. They will be an identical variety to the parent plant.