Help with water filtration (reverse osmosis?) system

[Toddg]

We recently moved into a home that has a water system (picture attached).  
There is a water dispenser at the sink and in the fridge.  The stream comes out well to start with but trickles by the time the glass is full.
Can someone tell me how to get my system working and how to change the filters?  Should I replace the filter in the fridge also?  Currently there is not one there.  

[richm20]

RO is VERY slow to produce water. Looks like you have a 3 (or so) gallon tank, once empty that could take 3 hours to fill back up. Is your issue of little to no water happening all the time or perhaps after you have used a bunch of water previously? If you wait 2 hours for it to fill and you still are getting very little water, the storage tank may be bad. If you shake the tank and hear/feel water sloshing around, your tank has a leak. Full, or not, the tank should never slosh.