The four supported types of SPICE simulation are as follows.
No options apply, just click the Simulate button. An O.P. analysis is useful when you want to view information such as voltages or current levels at startup.
In this case, you want to vary one voltage or current, and see the DC response of the circuit, for example to see how it reacts when the power supply goes from 0 to 3V. From the Source dropdown, choose an independent voltage/current source (a part that was mapped to an independent source SPICE type when it was mapped) and give the start and end values for the sweep.
In this case, you want to simulate your circuit over a range of frequencies, for example to see if an amplifier will work well with low and high frequency input.
Choose the AC sweep type (Dec = decade / log scale, Lin = linear scale), and set the start and end frequencies.
If you choose a Transient analysis, you will simulate your circuit over time. Set the Start time and End time. For example, you might want to simulate a 1-second timer circuit over time, from 0 to 5 seconds, to view the timer operation works as designed. TMAX is an advanced setting used to set the maximum time step that the simulator should use; you can leave it blank. The default value should be good for most situations.
For AC, DC, and Transient, setting the number of points is important as well. The Points field is the number of points you set to tell Electronics how fine of a step resolution to simulate to. Because the simulator may use more points that you initially requested, the Max points field is used to make sure the plotter never tries to plot too many points. Set Points to something between 200 and 500, and set Max points to 1000 for typically best results.