Firstly, type in 4575 Camino De La Plaza, San Ysidro, CA 92173 or (324 Virginia Avenue, San Diego, California 92173) on your GPS, when you arrive you will see a sign "Mexican insurance and parking". You can park your vehicle in the parking lot, the fee is $5 and its for 24 hrs and you can get your money changed into Mexican pesos and pay for parking in the building labelled "baja-mex insurance". After just walk along Virginia Ave towards the border crossing, make sure to have your passport with you. Its about a 2 minute walk, on arrival just walk into the walkway that says "to Mexico", follow the path, after about 3 minutes walking you will arrive at the Mexican immigration, fill out the immigration arrival form and produce your passport, your passport will be stamped with an entry stamp, then walk on to customs, after clearing customs follow the walkway and walk into Mexico. When you arrive into Mexico, about 3 minutes walk, you will see the Mexico-Tijuana sign, walk across the street towards the overpass, then turn left towards the hills, at the first intersection turn right, pass the pharmacy and other stores, then you will see a plaza on the right (about 2-3 minutes walk), walk through the plaza, you should see the arc and a walkway in front of you, get onto the walkway, at the end of the walkaway turn right and get down on the small stairway, follow the walkway for about 1 minute then turn right, you the see the an entrance walkway with the a sign "welcome to Tijuana" continue walking and you will meet the town, all the walking together is less than 10 minutes, on returning just enter the USA crossing walkway following the same pathway that you took to Mexico, produce your passport to the USA immigration and you're back into the USA, its very simple, and does not cost any money to cross the borders, walk with a light jacket if its cold in the USA.