how to filter products by check box,when i filter products olny one section products will shown

i am new in php i have taken this example from net..i am unable to filter the products from my database plenter code hereease help me. how to filter products by check box,when i filter products olny one section products will shown and after i select another checkbox the previoues checkbox data will be not displayed on the page

My index page

Tour type

                            <ul>
                                <li>
                                    <label>
                                        <input type="checkbox" class="sort_rang" onclick="filter()" name="size[]" value="Activities">
                                        <i class="awe-icon awe-icon-check"></i>
                                            Activities 
                                    </label>
                                </li>
                                <li>
                                    <label>
                                        <input type="checkbox" class="sort_rang" onclick="filter()" name="size[]" value="Resorts">
                                        <i class="awe-icon awe-icon-check"></i>
                                                Resorts
                                    </label>
                                </li>
                                <li>
                                    <label>
                                        <input type="checkbox" class="sort_rang" onclick="filter()" name="size[]" value="functions">
                                        <i class="awe-icon awe-icon-check"></i>
                                            Events
                                    </label>
                                </li>
                                <li>
                                    <label>
                                        <input type="checkbox" class="sort_rang" onclick="filter()" name="size[]" value="tour">
                                        <i class="awe-icon awe-icon-check"></i>
                                        Tour
                                    </label>
                                </li>
                                                                     <li>
                                    <label>
                                        <input type="checkbox" class="sort_rang" onclick="filter()" name="size[]" value="rentals">
                                        <i class="awe-icon awe-icon-check"></i>
                                        Rentals
                                    </label>
                                </li>

                            </ul>
                        </div>