Introduction to Operational Amplifiers with LTSpice
LightningHawk 
Inverting Amplifiers
An example of an inverting configuration consists of one op amp and two resistors, R1 and R2. R2 is connected from the output terminal of the op amp to the inverting or minus terminal of the op amp. R2 closes the loop around the op amp.
One thing not mentioned in the video below, but is considered implied because we are still using the ideal op amp, is that no current flows through the op amp. All the current (I1) flowing through R1 is also flowing through R2. Another thing to note is that if R1 and R2 are equal in value then this circuit is typically used convert -vout to +vout (changes the phase). This is known as the unity-gain inverter.
Project: The Summing Amplifier
A typical application for an inverting amplifier is a summing amplifier, also known as a virtual earth mixer, used in audio mixing. I happen to have quite a few LM741 op amps lying around, so I went ahead and built a summing amplifier. First I modeled it in LTSpice.