There is a drain plug under the filter can to drain the oil out. Once drained, use a filter wrench to grip the filter can from below and unscrew.
The link below shows the filter can wrench.
Autoparts or auto tool stores should sell the wrench.
The can unscrews allowing replacement of the filter element.
The filter box should have new o-rings for the can and drain plug, make sure you change these.
The procedure should be about the same as the engine in the link below:
Make sure you use the same type and viscosity of oil, most likely a synthetic (check owners manual).
Don't rock the can when removing as this could damage the oil pickup tube.
The trans uses synthetic oil which is supposed to last a long time. There is no dip stick, the fluid level check is done with a plug on the side of the trans. To check the fluid requires a procedure to bring the fluid up to a certain temp.
The dealer is supposed to inspect the fluid color, then compare to a color chart to determine its condition and if it requires changing.