I want the length of my grass taller. How do I adjust the blade to achieve this? Or is it the wheels?

If the mower starts and runs, then shut it off.
Find the spark plug.
Now, tip the machine up on its side WITH THE SPARK PLUG UP.
(If you do not, and if you tip it the wrong way, you can fill the combustion chamber with oil and ruin the machine when you try to start it again.)
Once it is tipped, look under the machine, and feel the blade to see if it is tight or loose on the motor shaft, and also if it needs to be sharpened.
If loose, tighten it.
If dull, sharpen it.
God bless your efforts.

thats normal but if you want it could be a govenor has come out of adjustment take it in to check it should cost 30.00

Have you changed springs? Likely the correct components are there unless you have changed it. Does it run properly and at correct rpm when not in tall grass? Check for proper throttle adjustment first. also check for obstructions (packed grass for instance) under the deck that could be impeding the blade. Lastly, if you have the discharge blocked with a mulch plug, remove the plug. let the tall grass discharge. then run over it again and mulch it.

if you look under lawn mower were the deck attachs you will see the adjustment rods unhook one at a time to adjust ether screw the rod in or out do this on a driveway so you can measure with the tape measure how for you or lifting deck and can match hight on both sides

Sounds like a broken shear pin in the drive pulley. Check the belts and see if they are slipping. Broken shear pin will not let the blades spin under pressure. .

That is the most likely cause of the problem - taller and thicker grass the blades encounter more resitance and the drive belt slips and it doesn't cut. This would likely cause a juddering of the machine when it occurs.

Hope this helps.

You may have worn blades that dont overlap anymore.

You should take your blades off and have them compared to new blades and see if they are a little shorter than they used to be.
If not....have them sharpened and put them back on. Check your Swishers belt tensioner to make sure the blades are all turning freely.

Is this the first time cutting grass with a lawn tractor?
How tall of grass?
Use the grass cutting heigth adjustments on the tractor to a higher setting when cutting tall grass. Cut again to a lower height setting on the second pass. Grass higher than your tractor is not good for your tractor. Follow the manual instructions for best results.

Riding mower decks are typically canted (offset) to avoid this issue. Double check to verify the new blades are the same length as the original blades.
Not all mower blades are created equally, universal replacement blades do not adhere to the same standards as OEM blades for size, hardness or many additional standards built into the OEM blades when the mower deck was designed.