Transmission issues with my 1999 Honda CR-V?

Ok so I'm clearly having issues with the transmission with the car because the car won't switch gears when I get up to 40 it just keeps revving itself up and it just makes a loud sound, and I also saw a dark brownish fluid leaking from under the car up towards the front area. I haven't checked the transmission fluid nor do I know how to.

You really need to change your transmission fluid every so often. Along with the oil, with a car this old. As a result, stuff like this can happen. Not saying that is the case however. Refer to your owners manual for where the dipstick is located or look it up online. If you have never changed it just change it now. If it has been a few years change it. Sometimes my car 06 crv would shift gears "hard" sometimes. After I replaced the fluid it went away. Not sure what that dark liquid would be. Is it thick?