New to Docker ... help with container & images

Hello … I’m new to Docker so I could use some help … My host is runnng Centos 7 (Linux eng-rig23.pace.internal 3.10.0-123.el7.x86_64 #1 SMP Mon Jun 30 12:09:22 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux) What I’m trying to do is run gdb which was build on a 2.6 kernel on centos 7 which I believe docker can help. I’ve installed the docker packages … and pulled a centos 6.6 image …I ran "docker run -t -i jdeathe/centos-ssh-apache-php:latest /bin/bash and I believe it comes up in a bash window … everytime I rerun it creates another container id … So I’m asking what’s the best way to create a container install an image and copy my gdb app into the container so I can run it in the same container every time …

Thanks in advance

Dale G. (