how to apply open sans font with size 24px and color code #666666 for a tag ?

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CSS3

Hi Friends,
How to apply open sans font with size 24px and color code #666666 for a h1 tag inside td. I need to apply for highligted Leave management system

<tr>
            <td style="background-color:#F3F3F3;">
                <table  width="100%" style="background-repeat:no-repeat;height:100px" cellpadding="0px">                   
                    <tr>
                    
                        <td  style="removed: relative; removed 0px; removed 188px;" width="85%" height="100px" >
                        <h1 style="removed: relative; removed 0px; removed 10px;">Leave Management System</h1>
                        </td>
                        <td style="removed: relative; removed 0px; removed 0px;" width="15%" height="100px"><img alt="" src="Images/LMSNewBannerLogo.PNG"
                          /></td>
                         <%--<img alt="" src="Images/LMSNewBanner.jpg"   
                        style="position: relative; top: 0px; left: 0px;" width="100%" height="147px" />--%>
                        
                                          
                    </tr>
                   
                </table>
            </td>
        </tr>