add brief description to README

README.md

@@ -2,3 +2,29 @@ rapl-tools
 ==========
 
 Tools for monitoring CPU power with Intel's RAPL interface
+
+Project contents
+-------
+AppPowerMeter - Measures the energy and monitors the power of an app
+PowerMonitor  - Monitors CPU power of the system 
+Rapl.cpp      - CPP class designed to function as a RAPL interface 
+
+Running
+-------
+AppPowerMeter is a commandline wrapper for application commands. For example,
+```
+./AppPowerMeter sleep 5
+```
+will measure the total energy and average power of the CPU while it runs "sleep 5". The CPU power is sampled every 100ms then written to rapl.csv. 
+
+The csv column headings in rapl.csv are "pkg, pp0, pp1, dram, time", measured in watts. See the Intel specification for more information about the different measurement types. 
+
+Building
+-------
+The project is built with Gnu Make. G++ >= 4.7 is required.
+
+```
+make
+```
+
+