Hi Josabel,
Congratulations on your recent graduation!
Are you sure that the reason you weren't selected is because you lack the experience they need? I only ask because in order to improve your job prospects it is important to be clear and accurate about the source of the problem. Let's assume that it is your lack of experience. Do you know exactly what kind of experience? Is it working with a certain population? Is it assessing certain types of functions? You get the idea. The more specific you are the easier will be to get some experience. It is OK to ask for feedback after an interview and find out "how could I become a stronger candidate?"
One sure way to gain experience (once you know what is that they want that you lack) is to volunteer. Look for volunteer opportunities that will help you gain the experience needed to make you a desirable candidate. When offering to volunteer, make sure you have flexibility to go on interviews and secure the boss's assurance that they will give you a recommendation after a determined number of weeks/months (one, two, three).
Best of luck!
Anna
