To run a workspace, click Ctrl+R or click the Run 
tool. (In the New Workspace or wizard dialogs, you can simply click the OK button.)
FME will begin the translation, and you’ll see processing information in the log pane.
The amount of time the translation takes depends on different factors that may include: the processing power of the FME host machine, the size of your data, and the amount of processing that FME has to do. In most cases, however, a translation will take a few minutes at most, and upon completion, the log will display Translation was SUCCESSFUL. You can scroll back through the log to check specific statistics.
Note that if you haven't entered a name for the destination data, you will be prompted for a file or folder name.
A default workspace name will be assigned, based on your reader and writer formats (for example, dwg2dgn.fmw) but you can change this at any time.
How can I run a workspace and see the output before writing any data?
In most cases, after creating a new workspace or making changes to an existing one, you aren't going to simply run it and hope for the best. You'll want to inspect the output first and make sure it looks as expected.
There are several options for inspecting output data before you decide to write the data. For more information, see About Data Inspection.
For debugging purposes, you can also inspect the features of your data at different points in your workspace. For more information, see About Feature Inspection.
What if a Translation Fails?
If you see a message that says Translation Failed, the FME log will often be the best source to find out what went wrong.
Usually it will be something simple, like a missing file. Sometimes, however, you will have to perform some troubleshooting on either your source data or on the transformer properties. A good way to troubleshoot is to route your output to an interim FFS file, an Inspector, or a NULL output.
Information and Help
A good source of information and help is FME Knowledge Center.