There are a couple of options for doing this. Either use a JavaScript executor method or use Actions() method.
JavaScript Executor method:
JavascriptExecutor js = (JavascriptExecutor) driver;
js.executeScript("javascript:window.scrollBy(250,350)");
Actions method:
WebElement Elmnt = driver.findElement(By.id("my-id"));
Actions actions = new Actions(driver);
actions.moveToElement(Elmnt);
actions.perform()