It really depends on the accelerometer you are using. Some have analog out, some use the I2C or SPI bus. If it uses analog output, research the ADC on the PIC. If it uses I2C or SPI research those. Then take a thorough look through the datasheet. 99.9% of the time, if you know how to interpret them correctly, they have all of the info you need.
in addition to freeskier's sage advice look for application notes from the manufacturer. they will often go into more depth than a datasheet explaining how to use the product.