Working with ubuntu

Hi, I am currently working with ubuntu, whenever I try to run a gmt command, it always says GMTTRY.sh: line 4: gmt: command not found. What do I do to fix this?

Not much information to go on here. If you installed gmt via ubuntu then gmt is in your PATH unless you made some manual changes to your environment. If which gmt returns nothing then GMT is not propoerly installed or your path is wrong.