apps not opening

[cujoe127]

i have tried to download several different things and that goes fine. Then i mount it that goes good, but when i try to open it to install there are lines that look like a window opening but nothing happens or some apps says quicktime does not recognize the file could not open. I am running os x 10.2.8 and quicktime 6.5.3 I have tried to install 6.5.2 quicktime but it says a newer version is on the computer. so i deleted it but it says it is still there when i try to install 6.5.2 PLEASE HELP ME