Welcome to the forum.
The manual slide locks can sometimes be moved by hand by pushing the clamp in center up to unlock or pushing down center to lock.
If locks have not been used before the slide has not been compressing the seal for easy application. Will find picture for you. The bedroom locks will be difficult to see and may need a flashlight to see in crack space.
The slide topper if to tight will hold top of slide from moving out so bed may lift up. The locks clamp have a ball bearing inside clamp which you can see when beds inside, a drop of 3n1 oil may help in operation of locking bar.
The rubber seal around slide should be compressed so no air or water, if raining while driving, will not blow in.
The end with two hooks will hook depending on intent to lock or unlock bar, hook on the bar close to wall and the pin in center will hook on top the center clamp to push down to lock or under the clamp to lift up to unlock. Practice on the large slide out front where there is more room to see what your trying to do. If the bar seems to lose you can remove it from wall and gently tap clamp with ball bearing to close clamp slightly to grip bar better. --
PICTURE
Some links you need,
important links for Newmar owners, all the links below in my signature have answers to problems for your Newmar,
Brochure,
Owners Guide,, help in getting
around irv2.