The most effective way to drive traffic to your ecommerce store with Facebook Ads is to create a campaign specifically designed to promote your website. You'll need to create an ad that includes a URL to your website, as well as a headline and description that explain what users will find when they click through to your site.
You can also use Facebook's targeting options to ensure that your ad is shown to the people most likely to be interested in what you're selling. For example, you can target people based on their location, interests, or demographics.
Once your ad is created, you'll need to set a budget for how much you're willing to spend on it. You can choose to run your ad on a daily or lifetime budget, and you can also set a maximum bid that you're willing to pay per click.
Once your ad is live, you'll need to monitor it closely to ensure that it's performing well. You can do this by checking your ad's click-through rate (CTR) and conversion rate. If your CTR is low, you may need to adjust your ad's targeting or budget. If your conversion rate is low, you may need to adjust your ad's copy or website design.