Dodge Interpid R/T 2000 keeps stalling Won't hold charge on New Battery

Car would not start,we replaced the Battery and one of the battery terminals as it was corroded.Car started up just fine,less than 24hrs.later the car is not starting.It started fine thorough out the day and now I am having the same problem with it not starting.Someone told me to check the starter relay in the power distribution box but how would I do that and where is it located? If its
not the starter relay,what else could be the problem?