You can get Quartus to produce a shell testbench file by selecting Processing | Start | Start Test Bench Template Writer.

There will now be a file in your simulation\modelsim directory. Open it.
The section near the bottom of the file is where you put statements for your simulation.

Insert instructions for how you want the inputs to change through the simulation.

Here's an example of the beginning for a very simple simulation:
After making the changes, you need to change the settings to include your testbench.

Choose a New testbench.

Give the test bench a name. It doesn't have to be the same as the file name.

Now add the testbench file.

Select OK to close the New Test Bench Settings window..

Select OK to close the Test Benches window..

Select OK to close the Settings window..

If it's not open, open the testbench VHDL file using File | Open. Then add it to the project using Project | Add Current File to Project.

Compile the circuit for a functional simulation by selecting Processing | Start | Start Analysis & Elaboration.
Select Tools | Run EDA Simulation Tool | EDA RTL Simulation. ModelSim will display splash screen. ModelSim will load libraries and compile the project. The transcript pane at the bottom of the screen indicates the scripts that have been run (or are running).
Now your work library will contain two VHDL files; your circuit and your testbench. Select both, and right click to compile both.
Select Simulate | Start Simulation to put ModelSim in simulator mode. The Start Simulation Window opens.
The Start Simulation window contains many tabs. The Design tab lists the designs available for simulation; most are system libraries. At the top of list will be work (default name for the library containing your program), expand work by selecting the '+'. All components in your design will be listed, select the component that is the testbench.

Select OK. This will bring up other panes.
Then the left hand side of the screen should now contain a sim tab that displays the design units in your circuit and the supporting libraries. When a design unit is selected in the sim tab, the corresponding signals are shown in the objects window on the right hand side of the screen. Signals that are preceded with a plus (+) sign indicate a bus (a group of wires with common function).

For each signal that you want to add to the simulation, right click on the signal name in the Objects window and select Add | To Wave | Selected Signal. Typically, you would want to add all inputs and outputs. A waveform window will appear in the work area.
Alternatively, you can add a range of signals at once by selecting the 1st signal and then, while holding down the shift key, select the last signal in the range. Then right click in the selected signal region and select Add | To Wave | Selected Signals. A waveform window will appear in the work area.
When all signals are selected, expand the Wave window.
If the Wave window is not floating above the ModelSim main screen, use the top left icon in the wave window to undock the window. Expand the detached window.
In the tool icons, find the window that contains the period of the signal, e.g. 100ns. Immediately to the right of that window will be the run simulation icon (looks like a page with a blue down arrow beside it). Click on it to run the simulation.
You should see the inputs that you entered and the outputs from your system on the waveform. The period of the run will correspond to the time in the period window. All signals should be green. If any signals are red, then one or more of the inputs was not specified.