First, I would call into question the assumption that you (or people more generally) necessarily have a definite, specific "spirit guide." I don't have a problem with the idea. If you want to run with it, that's fine, and I have no doubt you can make that work for you. But I just want to point out that this is just one way of imagining your relationship to the spirit world.
But as for how to do this, there are a huge number of ways. You could, for example, do the Abramelin ritual, or the numerous contact-your-HGA variations that people have created over the past hundred years. Here is how I would do it: start by assuming that your spirit guide is ready and available for communication, and that you just have to build up the channels of that communication.
The first step is to create an altar for your spirit guide. If you have no idea what to put on the altar, I would start with just a piece of unlined paper with the words 'Spirit Guide' on it. Or, if you have any ideas of symbols that your spirit guide might resonate with, or that suggest 'spirit guide' to you, then you can put those on the altar as well. In any case, this altar will evolve as your relationship with your guide develops and changes. But trust your intuition. If there is something that 'feels right' going on the altar, do it. Those subtle cues are the main way that your guide is going to communicate with you.
Second, start a daily (or, better, twice daily) practice of going to the altar, making an offering of some kind (incense, candle, water, or the like), and spending 15 minutes engaging with your spirit guide. This engagement should include a mix of speaking regular prayers that you write or come to through the process of engagement, speaking spontaneous heart communications, attuning your energy with that of the guide, and listening with your heart to the guide.
The art of listening could use some explanation. Basically, you need to start working with your imagination and learning to trust/discern what comes to you through your intuition as projected in your imagination. To start with, think to yourself, "what is my spirit guide like?" And start trying to imagine what they are like. Among other things, they are fucking awesome, so don't hold back in imagining your ideal spirit guide. Let your imagination fill in as many details as it can, and now you have your first impression of your guide. How do they make you feel? What kind of altar accoutrements would resonate well with them? Now, when you go to your altar to engage with them, you can start by coming back to these themes, images, and feelings as a starting point. From there you learn to rest your consciousness in that field and notice any shifts or new directions that the energy is asking you to attune to and explore. In this way, a relationship develops and the guide teaches you about how to engage with them.