1990 dodge omni auto transmission

I lost the forward gears on my wifes omni the fuiled level was low. I'm changing the oil and filter but I don't know how much to put in? It worket
fine then just find then all at once it just would not go in foward gear but it backs up just fine. It feels like it wants to go in gear.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.