There are various problems with your cron entry and your script.
First, your format for the cron fields (indicating time of execution) are wrong, you're using double commas and they should be single. Also, if you want this to run every 10 minutes, it's easier to do this:
*/10 * * * *
Next, the script part. Properly formatted, your script looks like this:
if [ -n "$RUNNING" ] ;then
else Bash ServerStart.sh
grep minecraft lacks a parameter, and the syntax to assign the result of a command to a variable is wrong, it should be something like:
RUNNING=`ps waux | grep minecraft`
but even that is not entirely correct, this is just an example.
Next, if the condition for the
if is met, you want to execute an "end" command which does not exist.
After that, the
else clause also specifies a non-existent command (it would be
bash in any case, not
if clause is not properly terminated, so it definitely won't work.
What you're trying to do is relatively straightforward, so even if you're just beginning with cron and shell scripting it will be easy, but I suggest you read some documentation first, so you can understand what you have to do, and have a document to refer to in case you need a quick refresher on how these commands work. If after reading this you're still having trouble, you're welcome to ask for comments and help.
First, a tutorial on how to use cron:
Then a bash programming tutorial: