It feels like I have air in my manual 6 speed transmission. I am having trouble getting it to go into gear.
It sounds like you are experiencing a hydraulic issue. Check your clutch fluid and see if it is at normal operating level. If not, top it off and see if that helps your issue. If not there could be an issue with the clutch master cylinder, clutch slave cylinder or the lines from each component. I would have a trained technician, like one from YourMechanic, diagnose your gear shifting issue to determine what repairs are needed.